COSTAL CHONDROSARCOMA MIMICKING BREAST CANCER: A RARE CASE REPORT AND REVIEW OF THE LITERATURE

Costal chondrosarcoma is the most common primary malignant tumor of the ribs. Its course is generally indolent, but its potential for local extension can be considerable. Involvement of breast tissue, which is exceptional in the literature, is an unusual clinical presentation that can easily mimic a primary breast tumor and thus make the diagnosis difficult. A rigorous radiological and pathological approach is therefore essential to guide management. The diagnosis of costal chondrosarcoma relies on a combination of clinical, radiological, and histopathological findings. Clinically, the lesion often presents as a firm, minimally painful chest wall mass that may extend toward the breast tissue, where it simulates a breast tumor. The diagnosis can only be established after excluding metaplastic carcinoma and malignant phyllodes tumor, through multiple samplings looking for evidence of in situ or invasive carcinoma. We report a case of costal chondrosarcoma mimicking breast cancer in a 48-year-old woman with no significant medical history, who presented with a right breast mass. The clinical appearance suggested a breast sarcoma, and histopathological examination was consistent with a grade II chondrosarcoma. Breast ultrasound and thoraco-abdomino-pelvic computed tomography (CT) were performed to assess the locoregional and distant extent of the tumor. We highlight the diagnostic difficulties encountered with the pathological samples and discuss the differential diagnoses.